This invention relates to filters and, more particularly, to an improved band rejection filter.
Band rejection, or notch, filters are in general more difficult and costly to implement than bandpass filters, which, for certain applications, have much less stringent requirements. It is therefore an object of the present invention to provide an arrangement which operates as a band rejection filter but utilizes a bandpass filter.
Certain communications systems operate in a first mode wherein all frequencies are passed and in a second mode wherein one or more frequency bands are rejected. It is therefore another object of this invention to provide an arrangement utilizing a bandpass filter in place of a notch filter which is selectively switchable to allow more than one mode of operation.